Abstract
Parastegodon is a valid genus, though it little differs from the genus Stegodon, and specialization is continuous from one to another. Japanese species of Parastegodon are closely related to the Malayan forms of the so-called Stegodon (mindanensis, trigonocephalus and airawana); the latter like the former are distinct from the genotype of Stegodon. Parastegodon contains the following species; P. aurorae (MATSUMOTO), P. mindanensis (NAUMANN) MATSUMOTO, P. trigonocephalus (MARTIN) SHIKAMA, P. airawana (MARTIN) SHIKAMA, P. akashiensis TAKAI, P. infrequens SHIKAMA and P. kwantoensis TOKUNAGA. From dental and cranological characters, Parastegodon is classified into three groups of airawana, akashiensis-aurorae and infrequens-kwantoensis. It is an oriental stock, having intermediate characters between Stegodon and Archidiskodon. In Japan it seems to have dissappeared at the end of the Tertiary owing to its catagenetic declination.
